1. Field of the Invention
The filed of the invention is that of caulking guns. The invention is an improvement as described in detail hereinafter.
2. Description of the Prior Art
Caulking guns as such are well known in the art and widely used. Typically, conventional caulking guns are constructed to provide a cradle to receive a cartridge containing caulking compound which has a dispensing nozzle at one end and a piston within it which acts against the compound.
The caulking gun has a reciprocating stem having a thrust disk at the end which acts against the piston in the cartridge to force the caulking compound out of the nozzle. Typically, the stem is actuatable by a manual lever or trigger which actuates a driving dog which reciprocates the stem when the trigger is manipulated. Typically, the actuating dog acts against a spring. Prior art guns are shown in U.S. Pat. Nos. 1,986,166; 2,530,359; 2,561,825; and 4,081,112.
A problem with caulking guns has been that when operation of the gun is discontinued the flow of compound from the nozzle would continue because of failure of the force or pressure on the piston in the cartridge to be released. In some guns this problem is considered to be solved in that the construction always allows the stem to freely move rearwardly when it is not engaged by the driving dog for moving it forwardly.
Caulking guns are known which include latching means including a latch dog which engages the stem near the handle and which allows forward movement of the stem but which prevents backward movement unless this latch dog is released. Release of the latch dog allows the stem to move backward freely thus, relieving pressure against the cartridge piston.
Aside from the problem referred to above, there has been a significant deficiency in known caulking guns. This deficiency resides in the fact that the operator does not know the position of the rod and thrust disk and the piston in the cartridge such that at times after all of the compound has been driven out of the cartridge the piston is forced against the end member of the gun so as break it loose from the cradle to which it is secured. The herein invention, a detailed description of which appears hereinafter, is constructed whereby to overcome this deficiency and to prevent the end member or fitting of the gun from being broken off. The invention is intended to provide the improvement both in guns wherein the pressure or force on the driving stem is automatically released or in guns wherein the stem is released for rearward movement by way of a thumb latch.